I tend to take a combination of a spiritual and psychological stance in regards to my therian and kin identities.
Most folks know that I’m a baby spirit worker, and I spend some time being aware of the astral. So my shapeshifting there, comments made by Loki, and astral dreams I’ve had all contribute to my pile of personal evidence for the validity of my claims. Emphasizing personal, because it really doesn’t count for shit as evidence to anyone but me.
I also feel a deep spiritual connection to my therio-/kintypes that pushes me to search for spiritual explanations.
However, as one pursuing psychology and in possession of critical thinking skills and rational thought, I also totally accept the possibility that I could identify this way due to a neurological difference, or through childhood influences, or as a means of self-empowerment. None of these mean my identity is invalid. They just mean I percieve myself on an internal, personal level differently than other, and if this helps me and hurts no one else, then it shouldn’t be an issue.